Currently available computer printers are adapted to print on a variety of mediums, and each medium may have a variety of formats. The medium is most commonly paper, but it may also be plastic, or some other material. The format may be lengthy continuous forms or discrete items such as cut sheets or envelopes. Regardless of the medium or format, they are referred to as webs in this application. Some or all of these webs may include edge perforations compatible with pin wheel or tractor type drives. Alternatively, these perforations may be omitted, provided the printer has some other means for engaging and moving the web, such as rollers.
Each printer usually structurally defines a path along which the web is transported as it progresses past the print head or other means for printing upon the web. Alignment of the web in this path is critical to proper operation of the printer, from both the mechanical standpoint of starting, moving, and stopping the web, and the aesthetic standpoint of properly orienting and aligning the printed information on the web. Improper alignment usually results in jamming of the means for moving the web, tearing or otherwise destroying the web, ripping or decoupling the edge perforations from the web, undesirably wrinkling the web, which may even damage the ribbon, platen, print head, or other parts of the printer. In addition to the resulting damage to the web or printer, there is down time resulting in a loss of productivity, and the necessity of reprinting all of the information.
This problem of keeping the web aligned in the web path is aggravated by the cumbersome problem of trying to properly align the delicate web with the printer during web loading operations. Unless the approach angle of the web to the printer is exactly zero degrees, any error in alignment will compound itself as the web is moved through the printer. It makes no difference whether the web is short (i.e. a cut form or envelope) or long (i.e. a continuous fan-folded web), any misalignment can be fatal to proper advance of the web and operation of the printer.
In the past, when loading a web into a printer, both hands of the operator were needed to grasp the opposite sides of the web, hold it taut, align it, and position it so that it could be gripped by the web advance means for feeding through the printer. However, with both of the operator's hands occupied holding the web, there was no convenient way to slow or manually operate the web advance means and ensure proper alignment during loading. For instance, while the web advance means was deactivated, the operator had to engage the web with the web advance means by either manually turning a web advance knob or by hand guiding the paper through the paper path. In knob type manual loading, the operator needed to grasp opposite sides of the web, hold it taut, align and position it with respect to the web moving means, and then turn the web advance knob. A problem encountered in the prior art was coordinating all the various steps with one hand while turning the web advance knob with the other hand. In the hand guide method of the prior art, first the operator had to release and disengage the web advance means to provide an unobstructed access for the web, then the web had to be hand guided into the paper path and pushed through until it came into position between the ribbon and platen. The operator then had to align and position the web and engage the web advance means without disturbing the web. A problem of this method was that the web would tend to fall out of position and alignment when the operator's hand was removed from the web to engage and close the web moving means. The magnitude of these problems increased with increases in the length and width of the web, and higher web advance speeds.
This problem has been addressed in the past, but solutions have required the use of auxiliary feeding apparatus that is external to the printer, and that must be manually positioned and operated. (See U.S. Pat. No. 3,722,655 to Singer). Other proposed solutions involved stopping the machine and physically changing the gears to slow the speed of web movement or to resume normal operating speed. (See U.S. Pat. No. 4,124,435 to Stump et al.)
In view of the foregoing, it is an object of the present invention to provide a method and apparatus for loading a web into a printer.
It is a further object of the present invention to provide a printer having a web moving apparatus with a first web advance mode for normal operation and a second web advance mode for loading the web into the printer.
It is a further object of the present invention to provide a method and apparatus to facilitate loading a web into a printer and advancing the edge of the web to a predetermined position.
It is a further object of the present invention to provide a method and apparatus for loading a web into a printer which frees the hands of the operator for proper positioning of the web in the printer while operating the web engaging and moving apparatus at a slower than normal rate.
It is a further object of the present invention to provide a method and apparatus for loading a web into a printer which uses existing printer components and does not require external apparatus.
It is a still further object of the present invention to provide a method and apparatus for loading a web into a printer with only minor modification or adjustment of the printer.
These and other objects are accomplished by generally providing a method and apparatus for loading a web into a printer. The printer comprises means for recording information on a web, which defines a print station. Further included is means for engaging and moving the web through the print station, and signal means for generating a normal mode signal and a load assist mode signal. A means for driving the means for engaging and moving the web is responsive to the normal mode signal from the signal means for operating the printer at a normal rate, and responsive to the load assist mode signal from the signal means for operating the printer at a slower than normal rate. The slower rate is used during web loading operations and facilitates alignment and engagement of the web with the means for engaging and moving the web.